Detector, detector assembly, radiation imaging system and method

Abstract

The invention provides a detector, a detector assembly, a radiation imaging system and a radiation imaging method. The detector comprises a semiconductor layer which is used for receiving incident photons and generating electron hole pairs; the electrode assemblies are arranged on the two sides of the semiconductor layer and used for applying bias voltage to form an electric field in the semiconductor layer so as to collect electric signals formed by the electron-hole pairs; the rear-end signal processing circuit comprises a signal shunting module, a counting branch and an integrating branch, and the signal shunting module is used for dividing the electric signal into two paths; the counting branch comprises a threshold comparator and a counter, the threshold comparator is used for comparing the amplitude of the input electric signals with a preset energy threshold, and the counter is used for counting the electric signals exceeding the preset energy threshold; and the integration branch comprises an integrator, and the integrator is used for accumulating the input electric signals.

Description

Technical Field

[0001] This disclosure relates to the fields of detectors and radiation imaging technology, and more specifically, to a detector, detector assembly, radiation imaging system, radiation imaging method, electronic device, computer-readable storage medium, and computer program product. Background Technology

[0002] With the development of radiation imaging technology, radiation imaging systems and methods are widely used in various fields such as security inspection, medical diagnosis, and ore sorting. Currently, energy integrating detectors can be used to detect radiation in radiation imaging systems and methods. Energy integrating detectors sum and record photons of different energies, resulting in low energy spectrum resolution and insufficient accuracy in material identification. With the development of electronics and integrated circuits, photon counting detectors have gradually matured. Photon counting detectors can distinguish photon energy and filter out low-energy noise, and have high energy spectrum resolution. However, photon counting detectors suffer from pulse accumulation problems. For example, in photon counting detectors, due to the non-infinitely short counting period, when two or more photons enter the detector within the same counting period, electrical pulses overlap, causing pulse accumulation. This accumulation effect further leads to a decrease in low-energy counts and an increase in high-energy counts, resulting in distortion of the radiation energy spectrum and affecting the true results of the image output. Summary of the Invention

[0003] In view of this, embodiments of the present disclosure provide a detector comprising: a semiconductor layer for receiving incident photons and generating electron-hole pairs; an electrode assembly disposed on both sides of the semiconductor layer for applying a bias voltage to form an electric field within the semiconductor layer, thereby collecting electrical signals generated by the electron-hole pairs; and a back-end signal processing circuit including a signal splitting module, a counting branch, and an integrating branch, wherein the signal splitting module is used to split the electrical signal into two paths; the counting branch includes a threshold comparator and a counter, the threshold comparator is used to compare the amplitude of the input electrical signal with a preset energy threshold, the counter is used to statistically count electrical signals exceeding the preset energy threshold; and the integrating branch includes an integrator, the integrator being used to accumulate the input electrical signal.

[0004] In another aspect, embodiments of this disclosure provide a detector assembly including at least one row of first detectors, the first detectors being detectors as described above.

[0005] For example, the detector assembly further includes at least one row of second detectors, which are energy integration detectors.

[0006] For example, the detector assembly further includes at least one row of third detectors, which are photon counting detectors.

[0007] For example, the energy integration detector includes: a scintillator crystal layer for receiving incident photons and converting the energy of the incident photons into an optical signal; and a sensor layer attached to the scintillator crystal layer for receiving the optical signal output by the scintillator crystal layer, converting the optical signal into an electrical signal, and integrating the electrical signal to obtain a total energy correlation signal of the incident photons.

[0008] For example, the scintillator crystal layer has a single-layer structure, and the single-layer scintillator crystal layer is located on the light-receiving surface of the sensor layer, used to uniformly convert the energy of the incident photons into optical signals; or, the scintillator crystal layer has a double-layer structure, the double-layer scintillator crystal layer includes a first scintillator sublayer and a second scintillator sublayer arranged along the propagation direction of the incident photons, the first scintillator sublayer is used to absorb incident photons with a first energy and convert them into a first optical signal, the second scintillator sublayer is used to absorb incident photons with a second energy and convert them into a second optical signal, the first energy being lower than the second energy; or, the scintillator crystal layer has a multi-layer structure, the multi-layer scintillator crystal layer includes m scintillator sublayers arranged along the propagation direction of the incident photons, where m is a positive integer greater than or equal to 3, the material composition and / or thickness of each scintillator sublayer is arranged in a gradient along the propagation direction of the incident photons, the gradient-arranged m scintillator sublayers are respectively used to absorb incident photons of different energy ranges and convert them into m optical signals.

[0009] In another aspect, embodiments of this disclosure provide a detector assembly comprising at least one row of second detectors and at least one row of third detectors, wherein the second detectors are energy integration detectors and the third detectors are photon counting detectors; the energy integration detector comprises: a scintillator crystal layer for receiving incident photons and converting the energy of the incident photons into an optical signal; and a sensor layer, attached to the scintillator crystal layer, for receiving the optical signal output by the scintillator crystal layer, converting the optical signal into an electrical signal, and integrating the electrical signal to obtain a total energy correlation signal of the incident photons; and the scintillator crystal layer has a single-layer structure, the single-layer scintillator crystal layer being located on the light-receiving surface of the sensor layer, for uniformly converting the energy of the incident photons into an optical signal; or, the The scintillator crystal layer has a double-layer structure, comprising a first scintillator sublayer and a second scintillator sublayer arranged along the propagation direction of the incident photons. The first scintillator sublayer is used to absorb incident photons with a first energy and convert them into a first optical signal, and the second scintillator sublayer is used to absorb incident photons with a second energy and convert them into a second optical signal. The first energy is lower than the second energy. Alternatively, the scintillator crystal layer has a multi-layer structure, comprising m scintillator sublayers arranged along the propagation direction of the incident photons, where m is a positive integer greater than or equal to 3. The material composition and / or thickness of each scintillator sublayer are gradient-arranged along the propagation direction of the incident photons. The gradient-arranged m scintillator sublayers are respectively used to absorb incident photons in different energy ranges and convert them into m optical signals.

[0010] In another aspect, embodiments of this disclosure provide a radiation imaging system comprising: a radiation source for emitting radiation for performing a radiation scan on an object under test; and a detector assembly for receiving at least a portion of the radiation after it has been attenuated by the object under test, wherein the detector assembly is a detector assembly as described above.

[0011] For example, the detector assembly is configured to acquire an energy integration signal and a photon count signal corresponding to at least a portion of the ray; the radiation imaging system further includes a signal processor electrically connected to the detector assembly, the signal processor being configured to: receive the energy integration signal and the photon count signal, and generate a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon count signal.

[0012] For example, generating a signal processing result for radiation imaging based on at least one of the energy integral signal and the photon counting signal includes: in response to the energy integral signal being less than a first preset value, establishing an equation based only on the photon counting signal; and solving the equation to obtain the signal processing result for radiation imaging.

[0013] For example, generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: in response to the energy integration signal being greater than a second preset value, establishing an equation based solely on the energy integration signal; and solving the equation to obtain the signal processing result for radiation imaging.

[0014] For example, generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: in response to the energy integration signal being between a first preset value and a second preset value, jointly establishing an equation based on both the energy integration signal and the photon counting signal; and solving the equation to obtain the signal processing result for radiation imaging.

[0015] For example, the left-hand side of the equation includes the incident energy spectrum incident on each detector of the detector assembly, and the right-hand side of the equation includes the equivalent energy spectrum emitted by the X-ray source and the attenuation ratio function.

[0016] For example, the step of establishing the equation based on both the energy integration signal and the photon counting signal includes: performing stacking correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal.

[0017] For example, the step of performing pile-up correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal includes: obtaining the luminous flux of the incident photons based on the energy integration signal; obtaining the probability of photon pile-up based on the luminous flux of the incident photons and the dead time of the first detector or the third detector; obtaining a first measured energy spectrum corresponding to the photon counting signal based on the photon counting signal; and correcting the first measured energy spectrum according to the energy integration signal, the luminous flux of the incident photons, and the probability to obtain a first incident energy spectrum.

[0018] For example, the step of jointly establishing the equation based on the energy integration signal and the photon counting signal further includes: obtaining a second incident energy spectrum corresponding to the energy integration signal based on the energy integration signal; generating an incident energy spectrum based on the first incident energy spectrum and the second incident energy spectrum, wherein the incident energy spectrum is an energy spectrum under n energy intervals, and n is the sum of the number of energy windows corresponding to the photon counting signal and the number of crystal layers corresponding to the energy integration signal; and constructing the left-hand side of the equation using the generated incident energy spectrum.

[0019] For example, solving the equation to obtain signal processing results for radiation imaging includes: iteratively solving the equation to decompose it into coefficients of multiple basis functions; and obtaining material information based on the coefficients of the multiple basis functions.

[0020] For example, the radiation imaging system further includes a collimator disposed at the emission end of the radiation source for collimating the radiation emitted by the radiation source so that the collimated radiation covers the detector assembly with a preset radiation field.

[0021] For example, the radiation imaging system is a digital X-ray imaging system, and the signal processing result includes at least one of transmission grayscale information and material information; or, the radiation imaging system is a computed tomography system, and the signal processing result includes at least one of transmission grayscale information, density information, material information, and basis function coefficient information.

[0022] In another aspect, embodiments of this disclosure provide a radiation imaging method, the radiation imaging method comprising: controlling a radiation source to emit radiation for radiation scanning of an object under test; receiving at least a portion of the radiation after attenuation by the object under test through a detector assembly, and acquiring an energy integration signal and a photon counting signal corresponding to at least a portion of the radiation; generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal; and generating a radiation image of the object under test based on the signal processing result.

[0023] For example, generating a signal processing result for radiation imaging based on at least one of the energy integral signal and the photon counting signal includes: in response to the energy integral signal being less than a first preset value, establishing an equation based only on the photon counting signal; and solving the equation to obtain the signal processing result for radiation imaging.

[0024] For example, generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: in response to the energy integration signal being greater than a second preset value, establishing an equation based solely on the energy integration signal; and solving the equation to obtain the signal processing result for radiation imaging.

[0025] For example, generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: in response to the energy integration signal being between a first preset value and a second preset value, jointly establishing an equation based on both the energy integration signal and the photon counting signal; and solving the equation to obtain the signal processing result for radiation imaging.

[0026] For example, the left-hand side of the equation includes the incident energy spectrum incident on each detector of the detector assembly, and the right-hand side of the equation includes the equivalent energy spectrum emitted by the X-ray source and the attenuation ratio function.

[0027] For example, the step of establishing the equation based on both the energy integration signal and the photon counting signal includes: performing stacking correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal.

[0028] For example, the step of performing pile-up correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal includes: obtaining the luminous flux of the incident photons based on the energy integration signal; obtaining the probability of photon pile-up based on the luminous flux of the incident photons and the dead time of the first detector or the third detector; obtaining a first measured energy spectrum corresponding to the photon counting signal based on the photon counting signal; and correcting the first measured energy spectrum according to the energy integration signal, the luminous flux of the incident photons, and the probability to obtain a first incident energy spectrum.

[0029] For example, the step of jointly establishing the equation based on the energy integration signal and the photon counting signal further includes: obtaining a second incident energy spectrum corresponding to the energy integration signal based on the energy integration signal; generating an incident energy spectrum based on the first incident energy spectrum and the second incident energy spectrum, wherein the incident energy spectrum is an energy spectrum under n energy intervals, and n is the sum of the number of energy windows corresponding to the photon counting signal and the number of crystal layers corresponding to the energy integration signal; and constructing the left-hand side of the equation using the generated incident energy spectrum.

[0030] For example, solving the equation to obtain signal processing results for radiation imaging includes: iteratively solving the equation to decompose it into coefficients of multiple basis functions; and obtaining material information based on the coefficients of the multiple basis functions.

[0031] Embodiments of this disclosure also provide an electronic device, including: one or more processors; and a memory for storing one or more computer programs, wherein the one or more processors execute the one or more computer programs to implement the steps of the method described above.

[0032] Embodiments of this disclosure also provide a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the method described above.

[0033] Embodiments of this disclosure also provide a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the method described above. Attached Figure Description

[0034] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0035] Figure 1 This is a schematic diagram of the structure of a radiation imaging system according to an embodiment of the present disclosure;

[0036] Figure 2A This is a schematic diagram of an X-ray source according to some exemplary embodiments of the present disclosure;

[0037] Figure 2B This is a schematic diagram of the energy spectrum of radiation emitted by a radiation source according to some exemplary embodiments of the present disclosure;

[0038] Figure 3 This is a schematic diagram of the detector structure according to some exemplary embodiments of the present disclosure;

[0039] Figure 4 This is a schematic diagram of an energy integration detector.

[0040] Figure 5A The schematic diagram illustrates the two-layer structure of the energy integration detector;

[0041] Figure 5B The schematic diagram illustrates the multi-layer structure of an energy integration detector;

[0042] Figure 6A This is a schematic diagram of the structure of a photon counting detector;

[0043] Figure 6B This is a hardware block diagram of a photon counting detector;

[0044] Figure 6C This is a schematic diagram illustrating the comparison process between the amplified electrical signal and a preset energy threshold in a PCD.

[0045] Figure 6D This is a schematic diagram used to illustrate the counting statistics of photons of different energies using PCD.

[0046] Figures 7A to 7E This is a schematic diagram of the structure of a detector assembly according to some exemplary embodiments of the present disclosure;

[0047] Figure 8A and Figure 8B The diagram illustrates the pulse stacking pattern in a photon counting detector.

[0048] Figure 9A and Figure 9B These are schematic diagrams of the equivalent energy spectra corresponding to photon counting detectors and energy integration detectors, respectively.

[0049] Figure 10 This is a flowchart of a radiation imaging method according to embodiments of the present disclosure; and

[0050] Figure 11 A block diagram schematically illustrates an electronic device suitable for implementing a radiation imaging method according to an embodiment of the present disclosure. Detailed Implementation

[0051] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0052] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0053] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0054] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0055] Digital radiography (DR) and computed tomography (CT) are two relatively mature radiographic imaging technologies. For example, in CT, DR data of the object under test at different projection angles can be obtained first, and reconstruction can be performed based on this data. Therefore, DR technology is fundamental to CT technology, and DR processing methods can serve as preprocessing techniques for CT. Since DR technology is fundamental, this disclosure uses DR processing methods as an example for illustration; the related imaging systems and methods are also applicable to CT imaging systems and methods.

[0056] In radiation imaging systems such as DR (Radio Reduction) systems, the detector can be an energy integrating detector (EID). An EID detector can include a scintillator crystal, for example, a single-layer scintillator crystal. Optionally, to obtain material information of the object under test, the EID detector can include a two-layer scintillator crystal. For example, it can be designed with two crystal layers: an upper low-energy crystal to obtain low-energy absorption spectrum data, and a lower high-energy crystal to obtain high-energy absorption spectrum data after absorption by the low-energy crystal. By fusing the high and low energy data into grayscale and performing dual-energy calibration, the equivalent atomic number of the object is obtained, generating a pseudo-dual-energy image. In other DR systems, the detector can include a single-layer scintillator crystal. By adjusting the energy of the radiation source or by superimposing a filter in front of the radiation source, true dual-energy data can be obtained, and a dual-energy image can be generated in one step. The inventors discovered through research that, regardless of whether it is a true dual-energy or pseudo dual-energy DR system, because they both use energy integration detectors, photons of different energies are summed and recorded together, so the energy spectrum they measure is not very distinguishable and the accuracy for material identification is insufficient.

[0057] With the development of electronics technology and integrated circuits, photon counting detectors (PCDs) have gradually matured. The inventors discovered that photon counting detectors have high discrimination of the energy spectrum and can accurately reproduce raw material information. However, photon counting detectors also have some problems. Limited by the fact that the counting period cannot be infinitely short, when two or more photons enter the detector within the same counting period, electrical pulse overlap occurs, resulting in pulse accumulation. This accumulation effect further leads to a decrease in low-energy counts and an increase in high-energy counts, causing distortion of the X-ray energy spectrum and affecting the true result of the image output.

[0058] To address at least one aspect of the aforementioned problems, embodiments of this disclosure provide a detector, detector assembly, radiation imaging system, and radiation imaging method that can use both energy integration signals and photon counting signals to obtain more accurate material results for the object under test, thereby obtaining a more accurate reconstructed image.

[0059] The detector, detector assembly, radiation imaging system, and radiation imaging method provided in the embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0060] Figure 1 This is a schematic diagram of a radiation imaging system according to an embodiment of the present disclosure. The radiation imaging system 100 may include a radiation source 10 and a detector assembly 20. The radiation source 10 can be used to emit radiation for radiation scanning of the object under test OB. Exemplarily, the radiation source 10 may include an X-ray machine, or any device for acquiring X-rays such as an isotope radiation source or accelerator. The collimated X-rays may be a fan beam, pencil beam, or other beam shape. The detector assembly 20 can be used to receive at least a portion of the radiation attenuated by the object under test OB. The detector assembly 20 may include, for example, detectors configured in at least one row. The detector assembly 20 may also include a support frame, such as a bracket, for supporting radiation-sensitive elements. Hereinafter, a detector pixel is used to represent the smallest unit of a detector; multiple smallest units can constitute a detector.

[0061] According to embodiments of this disclosure, a detector may include at least one row of detector pixels 201. The row of detector pixels 201 may be an array of detector pixels arranged in a certain direction. It should be understood that the array of detector pixels may be arranged laterally along the extension direction of the inspection channel used for moving the object under test OB, or in other words, the arrangement direction of the detector pixels is transverse to the transverse direction of the inspection channel. In this case, for example... Figure 1 As shown, the object to be measured, OB, moves in the direction Z indicated by the arrow, that is, from outside the paper to inside the paper. Figure 1The fan-shaped beam shown illuminates the object under test OB from the X-ray source 10. After passing through the object under test OB, the fan-shaped beam strikes the detector pixels of the detector assembly 20. Multiple detector pixels can be arranged vertically. It should be noted that... Figure 1 The arrangement of the detector assembly is shown only schematically. It should be understood that the detector assembly can have other shapes, such as L-shaped, arc-shaped, etc. The embodiments of this disclosure do not specifically limit this.

[0062] It should be noted that the detector assembly 20 may include multiple rows of detectors, which can be arranged along the row direction. Here, "row direction" can be understood as the relative movement direction between the object to be measured and the detector assembly. For example, in an object detection or ore sorting scenario where the object to be measured is moving, the object can move horizontally via a conveyor belt, and the row direction can be consistent with the movement direction of the conveyor belt. In a medical DR scenario, if the object to be measured is stationary while the detector assembly is moving, the row direction can be consistent with the movement direction of the detector assembly. Figure 1 As shown, the direction of the arrangement can be understood as the direction of movement of the object under test OB along the direction Z indicated by the arrow, that is, from outside the paper to inside the paper.

[0063] Figure 2A This is a schematic diagram of an X-ray source according to some exemplary embodiments of the present disclosure. Figure 2B This is a schematic diagram of the energy spectrum of radiation emitted by a radiation source according to some exemplary embodiments of the present disclosure.

[0064] Combined with reference Figure 2A and Figure 2B The radiation source 10 may include a housing 11, the interior of which may be a vacuum; and an anode 12 and a cathode 13 disposed within the housing 11. Under voltage U... h Under the influence of the generated high-voltage electric field, cathode 13 can emit electrons. Anode 12 may include a metal target. Electrons emitted from cathode 13 are subjected to a voltage U. a Under the acceleration effect of the generated high-voltage electric field, sufficient kinetic energy can be obtained to move towards the metal target. When the accelerated high-energy electrons bombard the metal target, on the one hand, the electrons interact with the atomic nuclei and extranuclear electrons of the target material, and are decelerated due to the braking of the Coulomb field of the atomic nuclei, thereby producing bremsstrahlung radiation. This radiation forms rays with a continuous energy spectrum, for example, the rays can include X-rays; on the other hand, the inner-shell electrons of the target material are excited by high-energy electrons. When the outer-shell electrons fill the inner-shell "holes", fluorescent X-rays are released. The fluorescent X-rays can be understood as characteristic X-rays.

[0065] The radiation source 10 may also include a support structure 14, which can support and fix the metal target, or provide initial guidance and shielding for the radiation, ensuring the stable operation of the radiation source.in The term refers to the substance (which may be a cooling medium, etc.) that enters the support structure 14 (e.g., a channel for cooling or other functions). For example, it can refer to the substance entering the channel of the support structure 14 for cooling or other functions; for example, the substance may include a cooling medium. out The term refers to the outflowing substance, which can be used to maintain environmental conditions such as temperature during the operation of the radiation source, ensuring that the radiation source can continuously and stably generate X-rays.

[0066] like Figure 2B As shown, the horizontal axis represents energy (keV), indicating the energy of each X-ray photon, measured in kiloelectron volts (keV). In other words, the horizontal axis represents the energy value, reflecting the distribution of photons with different energies. The vertical axis represents the relative count, indicating the relative intensity of the number of X-ray photons detected within a certain energy range. That is, the vertical axis reflects the "quantity" of photons with different energies; it should be understood that the value on the vertical axis is normalized, not an absolute photon count. The average energy represents the weighted average energy of the entire X-ray spectrum at a specific tube voltage (e.g., 40 kV, 60 kV, 80 kV, 100 kV). For example, as... Figure 2B As shown, at a tube voltage of 40 kV, the average energy of the emitted X-rays is 27.2 keV, indicating that although the maximum energy is 40 keV, most photon energy is concentrated around 27 keV. At a tube voltage of 60 kV, the average energy of the emitted X-rays is 34.8 keV. At a tube voltage of 80 kV, the average energy of the emitted X-rays is 41.8 keV, and at a tube voltage of 100 kV, the average energy of the emitted X-rays is 48.2 keV.

[0067] like Figure 2B As shown, the energy spectrum of the X-rays emitted by the X-ray source 10 is a continuous energy spectrum with characteristic spectral lines of the target material. When high-speed electrons collide with the target material (for example, the target material may include metals such as tungsten or molybdenum), the electrons are decelerated near the target atomic nuclei, and their kinetic energy is converted into X-rays, forming a continuous energy distribution. In the schematic diagram of the energy spectrum, the continuous spectrum is represented as an energy spectrum curve that first rises and then falls, starting from a certain minimum energy and extending to the maximum energy. This maximum energy can be approximately equal to the kinetic energy of the electron, that is, the energy corresponding to the tube voltage. For example, the maximum photon energy corresponding to a tube voltage of 100 kV is 100 keV. In addition to the continuous spectrum, the energy spectrum of the X-rays emitted by the X-ray source 10 can also contain characteristic spectral lines of the target material, such as... Figure 2BThe sharp peaks shown are characteristic X-rays. When high-speed electrons knock out inner-shell electrons from target atoms, outer-shell electrons jump to fill the vacancies, releasing X-rays with specific energies; these are characteristic X-rays. For example, the characteristic spectral lines of a tungsten target are approximately 59.3 keV and 67.2 keV. It should be noted that these characteristic spectral lines are fixed, and their energies are related to the element in the target material.

[0068] According to some exemplary embodiments of this disclosure, a detector 30 is provided. Figure 3 This is a schematic diagram of the detector structure according to some exemplary embodiments of this disclosure. For example... Figure 3 As shown, the detector 30 may include: a semiconductor layer 31 for receiving incident photons and generating electron-hole pairs; electrode assemblies 32 disposed on both sides of the semiconductor layer 31 for applying a bias voltage to form an electric field within the semiconductor layer 31, thereby collecting the electrical signal generated by the electron-hole pairs; and a back-end signal processing circuit 33, including a signal splitting module 331, a counting branch 332, and an integrating branch 333. The signal splitting module 331 is used to split the electrical signal into two paths. The counting branch 332 includes a threshold comparator 3321 and a counter 3322. The threshold comparator 3321 is used to compare the amplitude of the input electrical signal with a preset energy threshold, and the counter 3322 is used to statistically count electrical signals exceeding the preset energy threshold. The integrating branch 333 includes an integrator 3331, which is used to accumulate the input electrical signal.

[0069] Figure 4 This is a schematic diagram of the structure of an energy integration detector. (Example) Figure 4 As shown, the energy integrating detector (EID) 40 may include: a scintillator crystal layer 41 for receiving incident photons and converting the energy of the incident photons into an optical signal; and a sensor layer 42, attached to the scintillator crystal layer 41, for receiving the optical signal output by the scintillator crystal layer, converting the optical signal into an electrical signal, and integrating the electrical signal to obtain the total energy correlation signal of the incident photons. For example, the scintillator crystal layer 41 may include materials such as gadolinium disulfide (Gd₂SO₂) (GOS), gadolinium gallium aluminum garnet (GGAG), and cesium iodide (CsI).

[0070] For example, such as Figure 4As shown, the scintillator crystal layer 41 can have a single-layer structure. This single-layer scintillator crystal layer 41 can be located on the light-receiving surface of the sensor layer 42, used to uniformly convert the energy of incident photons into optical signals. Exemplarily, the sensor layer 42 can be a CMOS sensor layer, for example, it can include 1024×1024 pixel units, each of which can house electronic components such as photodiodes, charge amplifiers, and storage capacitors. During the operation of the energy integration detector, incident X-ray photons penetrate the object under test and enter the scintillator crystal layer. Through the photoelectric effect, they interact with crystal atoms, their energy is absorbed, and converted into visible light photons. For example, on average, each 50keV X-ray photon generates approximately 500 visible light photons. The visible light photons are transmitted to the CMOS sensor layer via the light-emitting surface, absorbed by the photodiode, and converted into photogenerated charges. These charges are amplified by the amplifier and stored in the capacitor for integration. After the integration period ends, the charge signal in the capacitor is converted into a digital signal by an analog-to-digital converter, ultimately outputting grayscale data reflecting the total energy of the incident X-rays during the integration time.

[0071] For example, such as Figure 5AAs shown, the scintillator crystal layer 41 can have a double-layer structure. The double-layer scintillator crystal layer 41 can include a first scintillator sublayer 411 and a second scintillator sublayer 412 disposed along the propagation direction of the incident photons. The first scintillator sublayer 411 can absorb incident photons with a first energy and convert them into a first optical signal, while the second scintillator sublayer 412 can absorb incident photons with a second energy and convert them into a second optical signal. The first energy is lower than the second energy. For example, the first scintillator sublayer 411 can be a low-energy absorption layer, serving as the main absorption unit for low-energy X-rays, capturing low-energy photons and converting their energy into a first optical signal. The second scintillator sublayer 412 can be a high-energy absorption layer, serving as the absorption unit for high-energy X-rays, effectively absorbing high-energy photons that penetrate the first sublayer and converting them into a second optical signal. For example, a filter layer can be provided between the first scintillator sub-layer 411 and the second scintillator sub-layer 412 to filter the scattered light generated by the first scintillator sub-layer, preventing the scattered light from interfering with the optical signal detection of the second scintillator sub-layer, ensuring the independence of the energy ranges of the two optical signals, and reducing energy spectrum distortion caused by cross-interference. Exemplarily, the sensor layer 42 can be a CMOS sensor layer. To accommodate the independent reading of the two optical signals, the CMOS sensor layer can be divided into two independent readout regions, precisely aligned spatially with the first and second scintillator sub-layers. For example, each readout region can include 512×1024 pixel units and can also be equipped with a dual sampling circuit to improve the signal-to-noise ratio. For example, during the operation of the dual-layer energy integrating detector, low-energy photons in the incident X-rays with energy below a preset energy value (e.g., energy < 30 keV) can be mainly absorbed by the first scintillator sub-layer and converted into the first optical signal; unabsorbed high-energy photons (e.g., energy ≥ 30 keV) penetrate the filter layer and are absorbed by the second scintillator sub-layer, converted into the second optical signal. The two optical signals are received by the corresponding readout areas of the CMOS sensor layer, and after photoelectric conversion and charge integration, two independent integrated signals are output: a low-energy integrated signal (corresponding to the energy range below 30 keV) and a high-energy integrated signal (corresponding to the energy range above 30 keV). In other words, in some embodiments, a dual-layer energy integrating detector for material identification can be provided. By absorbing X-rays in different energy ranges layer by layer and outputting two independent integrated signals, the energy spectrum of the analyte can be subdivided and the material properties determined.

[0072] For example, such as Figure 5B As shown, the scintillator crystal layer 41 can have a multi-layer structure. The multi-layer scintillator crystal layer 41 can include m scintillator sub-layers arranged along the propagation direction of the incident photons, for example... Figure 5BThe diagram shows multiple scintillator sublayers 410, where m is a positive integer greater than or equal to 3. The material composition and / or thickness of each scintillator sublayer 410 are set in a gradient along the propagation direction of the incident photon. The m gradient-set scintillator sublayers 410 are used to absorb incident photons in different energy ranges and convert them into m optical signals.

[0073] Figure 6A This is a schematic diagram of the structure of a photon counting detector (PCD). Figure 6B This is a hardware block diagram of a photon counting detector. (Example) Figure 6A and Figure 6B As shown, the photon counting detector 60 may include: a semiconductor crystal layer 61, electrodes 62, a signal preprocessing module 63, and a multi-threshold signal processing module 64. The semiconductor crystal layer 61 is used to receive incident photons and generate electron-hole pairs, the electrodes 62 are used to apply a bias voltage to collect electron-hole pairs, thereby forming an electrical signal, the signal preprocessing module 63 is used to amplify and reduce noise in the electrical signal, and the multi-threshold signal processing module 64 is used to perform energy spectrum measurement by threshold comparison.

[0074] For example, the semiconductor crystal layer 61 can be made of cadmium zinc telluride (CdZnTe, abbreviated as CZT) material, and the incident surface (the side facing the radiation source) of the semiconductor crystal layer 61 can be polished to reduce photon reflection loss.

[0075] For example, electrode 62 may include a cathode electrode 621 and an anode electrode 622. Cathode electrode 621 may include a large-area platinum thin film covering the incident surface of semiconductor crystal layer 61. Anode electrode 622 may have a pixelated structure, with gold material deposited on the exit surface of semiconductor crystal layer 61 (e.g., the side facing away from the radiation source). Each pixel unit may have an independent lead wire. Electrode 62 can be subjected to a DC bias voltage by an external bias power supply to form a uniform electric field along the thickness direction inside semiconductor crystal layer 61, thereby driving electron-hole pairs to separate and migrate to the corresponding electrode.

[0076] For example, the signal preprocessing module 63 may be electrically connected to each pixel unit of the anode electrode 622. The signal preprocessing module 63 may include a preamplifier 631 and a shaping circuit 632. The preamplifier 631 may employ a charge-sensitive amplifier structure to convert the weak charge signal collected by the anode electrode into a voltage signal and amplify it initially. The shaping circuit 632 may shape the amplified voltage signal into a Gaussian pulse to reduce baseline drift interference during subsequent threshold comparison.

[0077] For example, the multi-threshold signal processing module 64 can be electrically connected to the signal preprocessing module 63. The multi-threshold signal processing module 64 can include multiple independent threshold comparison units 641, for example, it can include four independent threshold comparison units 641, each corresponding to one of the four energy thresholds; and a counter 642. For example, the preset energy thresholds of the four threshold comparison units 641 can be set to 20keV, 40keV, 60keV, and 80keV respectively. Each threshold comparator can be used to compare the amplitude of the shaped Gaussian pulse with the corresponding threshold. When the pulse amplitude is ≥ the preset energy threshold, an effective level is output; otherwise, an invalid level is output. The counter 642 can be a four-channel synchronous counter used to statistically count the effective levels output by each threshold comparison unit, generating photon counting data for four energy ranges (e.g., 20-40keV, 40-60keV, 60-80keV, ≥80keV).

[0078] Figure 6C This is a schematic diagram illustrating the comparison process between the amplified electrical signal and a preset energy threshold in a PCD. Figure 6D This is a schematic diagram illustrating the statistical results of PCD counting photons of different energies. It should be noted that... Figure 6C In this diagram, the horizontal axis can represent time, and the vertical axis can represent the amplitude of the electrical signal, such as the amplitude of an amplified voltage signal or a Gaussian pulse signal; Figure 6D In the diagram, the horizontal axis represents photon energy, specifically the energy range of incident X-ray photons, while the vertical axis represents the number of photons counted. Specifically, the vertical axis represents the total number of photons deemed valid within a given energy range within a set counting period, reflecting the intensity of photons in that energy range. Figure 6C and Figure 6D In this document, green and red areas are used to represent different energy ranges or energy thresholds. This is only an illustrative representation and is not intended to limit the embodiments of this disclosure to only two energy ranges or energy thresholds. In the embodiments of this disclosure, more energy ranges or energy thresholds can be set.

[0079] For example, during the operation of a photon counting detector, incident photons (e.g., X-ray photons) penetrate the object under test and are incident perpendicularly onto the incident surface of the semiconductor crystal layer 61. They then undergo photoelectric effect or Compton scattering with the atoms in the semiconductor crystal layer 61, absorbing photon energy and exciting electron-hole pairs. For example... Figure 6A As shown, the bias voltage applied to electrode 62 creates an electric field within the semiconductor crystal layer 61. Electrons migrate towards the pixel unit of the anode electrode 622 under the influence of this electric field, while holes migrate towards the cathode electrode 621. No significant recombination occurs during this migration, and ultimately all electrons are collected by the anode pixel unit, forming a weak charge pulse positively correlated with the incident photon energy. Figure 6CAs shown, the charge pulse is transmitted to the signal preprocessing module 63, converted into a voltage pulse by the preamplifier 631, and then shaped into a stable Gaussian pulse by the shaping circuit 632. The shaped Gaussian pulse is input to the multi-threshold signal processing module 64. Four threshold comparison units 641 simultaneously determine the pulse amplitude. For example, if the pulse amplitude corresponds to a photon energy of 60 keV, then its thresholds are ≥20 keV, 40 keV, and 60 keV, and only <80 keV. The first three threshold comparison units output valid levels, and the fourth threshold comparison unit outputs invalid levels. The counter 642 counts the valid levels and classifies the photon into the "60-80 keV" energy range. Figure 6D As shown, after the sampling period ends, the counter 642 can output photon count data for multiple (e.g., 2, 4 or more) energy ranges, which can be used as the energy spectrum measurement results of the incident rays for subsequent material identification or image reconstruction.

[0080] Return to reference Figure 3 In some exemplary embodiments of this disclosure, detector 30 may be a simultaneous counting and integrating detector (SCID).

[0081] For example, in detector 30, semiconductor layer 31 may include cadmium zinc telluride (CdZnTe, or CZT) material. Electrode assembly 32 may include cathode 321 and anode 322.

[0082] For example, the signal splitting module 331 can be a high-frequency broadband power divider, whose output impedance can be matched to the counting branch 332 and the integrating branch 333 to ensure that the amplitude attenuation of the electrical signal after splitting is ≤0.5dB and the time delay difference between the two signals is ≤10ns, avoiding timing misalignment of the two branches. The threshold comparator 3321 of the counting branch 332 can be a high-speed voltage comparator (e.g., response time ≤50ns), and the preset energy threshold can be adjusted by an external digital-to-analog converter, for example, the adjustment range can be 10keV-100keV, and the adjustment step size can be 1keV. The counter 3322 can be a 32-bit synchronous counter with a counting frequency of less than or equal to 100MHz, which can store the counting data of each pixel in real time. The integrator 3331 of the integrating branch 333 can be quickly reset after the integration cycle ends, preparing for the next round of integration.

[0083] For example, the counting branch 332 can have multiple independent threshold comparators 3321, such as four independent threshold comparators 3321, each corresponding to one of the four energy thresholds. For instance, the preset energy thresholds of the four threshold comparators 3321 can be set sequentially to 20keV, 40keV, 60keV, and 80keV. Each threshold comparator can compare the amplitude of the shaped Gaussian pulse with the corresponding threshold. When the pulse amplitude is greater than or equal to the preset energy threshold, a valid level is output; otherwise, an invalid level is output. The counter 3322 can be a four-channel synchronous counter used to statistically count the valid levels output by each threshold comparator, generating photon counting data for four energy ranges (e.g., 20-40keV, 40-60keV, 60-80keV, and ≥80keV).

[0084] For example, during the operation of SCID, after the incident X-ray photons penetrate the object under test, they are incident perpendicularly to the incident surface of the semiconductor layer 31 and undergo photoelectric effect with the atoms in the CZT crystal. The photon energy is absorbed by the crystal atoms, and the valence band electrons are excited to the conduction band to form electron-hole pairs.

[0085] Under the electric field applied by the electrode assembly 32, electrons migrate towards the pixel unit of the anode 322, and holes migrate towards the cathode 321. After the electrons reach the anode, they form a weak current pulse through the pixel electrode. This current pulse is converted into a voltage pulse by the preamplifier. The peak value of the voltage pulse is positively correlated with the energy of the incident photon.

[0086] The electrical signal is transmitted to the signal splitter module 331, and is divided into two paths by the power divider: one input counting branch 332 is used to realize the photon counting function; the other input integrating branch 333 is used to realize the energy integration function. The two signals are transmitted synchronously without significant timing deviation.

[0087] In the counting branch 332, a threshold comparison can be performed first. The threshold comparator 3321 of the counting branch 332 receives the shunted electrical signal and compares its peak voltage with a preset energy threshold. If the peak value of the electrical signal is greater than or equal to the preset energy threshold, the comparator outputs a high level, indicating a valid photon; if the peak value of the electrical signal is less than the preset energy threshold, it outputs a low level, indicating an invalid signal. Then, counting and statistics can be performed. The high-level signal corresponding to a valid photon can trigger the counter 3322, which can accumulate and count valid signals in the same pixel unit to output photon count data. The output photon count data can be used as the photon count signal output by the SICD.

[0088] In the integration branch 333, signal accumulation can be performed first. The integrator 3331 of the integration branch 333 receives the shunt electrical signal and accumulates the charge of the voltage pulse through the integrating capacitor. The integrator continuously accumulates the charge to the integrating capacitor, forming an integrated voltage proportional to the total charge. Then, integration output can be performed. After the integration period ends, the integrator outputs an integrated voltage signal. For example, this voltage signal is converted into a digital signal by an analog-to-digital converter. The digital signal reflects the total energy of all photons incident on the pixel unit during the integration period. The output integrated voltage signal or digital signal can be used as the energy integration signal output by the SICD.

[0089] It should be noted that the signal processing architecture and operation of the integral branch 333 in SCID 30 can be referred to the description of EID 40 in this document, and the signal processing architecture and operation of the counting branch 332 can be referred to the description of PCD 60 in this document. In order to make the description in the manual more concise, they will not be described in detail here.

[0090] In the embodiments disclosed herein, SCID integrates the integration branch and the counting branch, combining the advantages of EID and PCD. This avoids the inherent defects of both EID and PCD, and improves performance in areas such as energy spectrum analysis, signal accuracy, and material resolution. For example, SCID can balance energy spectrum discrimination and signal stability, overcoming the performance limitations of a single detector. The counting branch of SCID inherits the energy resolution advantage of PCD, and can filter and classify photons of different energies through a threshold comparator, avoiding the energy spectrum confusion problem caused by the "summation and recording of photons of different energies" in EID detectors, thereby improving energy spectrum discrimination. At the same time, the integration branch of SCID retains the stability of "signal accumulation" in EID. Even in scenarios with large fluctuations in photon flux, it can still output a continuous, low-noise grayscale signal through energy integration, avoiding signal distortion caused by a sudden increase in photon flux in a single PCD, achieving a dual guarantee of high resolution and high stability.

[0091] Figures 7A to 7E This is a schematic diagram of the structure of a detector assembly according to some exemplary embodiments of the present disclosure. (Referring to...) Figure 1 as well as Figures 7A to 7D In embodiments of this disclosure, the detector assembly 20 may include at least one row of first detectors 21 (e.g., Figure 7AAs shown, the first detector 21 can be the detector 30 described above, i.e., a simultaneous counting and integrating detector (SCID). That is, the detector assembly 20 can be a single-type detector configuration containing only the first detector (SCID). In this case, the detector assembly 20 can include one or more rows of first detectors 21. In a multi-row configuration (e.g., two rows of first detectors 21), the multiple rows of first detectors 21 can be arranged along the row direction, and the pixel array of each row of first detectors 21 can be aligned with the irradiation area of ​​the X-ray source. In this case, a single row or multiple rows of SCIDs can independently achieve synchronous output of the energy integration signal and the photon counting signal without the need for additional detectors of other types, which simplifies the component structure and is suitable for scenarios with high integration requirements.

[0092] Optionally, such as Figure 7B As shown, the detector assembly 20 may further include at least one row of second detectors 22. For example, the second detectors 22 may be the detector 40 described above, i.e., energy integrating detectors (EIDs). That is, the detector assembly 20 may have a dual-row configuration of first detectors (SCIDs) and second detectors (EIDs). Exemplarily, the detector assembly 20 may include at least one row of first detectors (SCIDs) 21 and at least one row of second detectors (EIDs) 22. It should be noted that the scintillator crystal layer of the at least one row of second detectors (EIDs) 22 may be designed as a single-layer, double-layer, or multi-layer structure.

[0093] Optionally, such as Figure 7C As shown, detector assembly 20 may further include at least one row of third detectors 23. For example, the third detector 23 may be the detector 60 described above, namely a photon counting detector (PCD). That is, detector assembly 20 may have a dual-type configuration of first detector (SCID) and third detector (PCD). Exemplarily, detector assembly 20 may include at least one row of first detectors (SCID) 21 and at least one row of third detectors (PCD) 23.

[0094] Optionally, such as Figure 7D As shown, detector assembly 20 may further include at least one row of second detectors 22 and at least one row of third detectors 23. For example, the second detector 22 may be the detector 40 described above, i.e., an energy integrating detector (EID). The third detector 23 may be the detector 60 described above, i.e., a photon counting detector (PCD). That is, detector assembly 20 may include a three-type configuration of first detector (SCID), second detector (EID), and third detector (PCD). For example, detector assembly 20 may include at least one row of first detectors (SCID) 21, at least one row of second detectors (EID) 22, and at least one row of third detectors (PCD) 23.

[0095] In some exemplary embodiments of this disclosure, such as Figure 7E As shown, detector assembly 20 may include at least one row of second detectors 22 and at least one row of third detectors 23. For example, the second detector 22 may be the detector 40 described above, i.e., an energy integrating detector (EID). The third detector 23 may be the detector 60 described above, i.e., a photon counting detector (PCD). The at least one row of second detectors 22 and the at least one row of third detectors 23 may be arranged side by side along the row direction. That is, detector assembly 20 may contain a dual-type configuration of second detectors (EID) and third detectors (PCD).

[0096] It should be noted that the configuration of "at least one row" can include one row or multiple rows. In the embodiments of this disclosure, there is no particular limitation on the number of rows of detectors included in the detector assembly. For example, the configuration of "at least one row" can include one row, such as setting only one row of first detectors 21, and achieving signal acquisition through continuous scanning of a single row of detectors. It should be understood that the single-row configuration is suitable for scenarios with high requirements for detection efficiency and limited space for installation. As another example, the configuration of "at least one row" can include multiple rows of at least two rows. For example, one row of first detectors 21 and one row of second detectors 22 can be set, or two or more rows of first detectors 21 and two or more rows of third detectors 23 can be set, etc. Multiple rows of detectors can be arranged along the row direction. It should be understood that the multi-row configuration is suitable for scenarios with high requirements for detection accuracy and signal redundancy. In addition, the arrangement order of each row of detectors can be adjusted according to detection requirements, and the embodiments of this disclosure do not impose any particular limitations on it.

[0097] It should also be noted that when the detector assembly includes multiple rows of detectors, the detectors are arranged along the row direction, and the spacing along the row direction can be flexibly designed according to the detection requirements. For example, the multiple rows of detectors can be arranged closely, and the spacing between any two adjacent rows along the row direction can be less than or equal to 1 mm. Optionally, the detection areas of two adjacent rows of detectors can partially overlap. For example, the multiple rows of detectors can be arranged sparsely, and the spacing between any two adjacent rows along the row direction can be greater than or equal to 5 mm, with no overlap in the detection areas of two adjacent rows of detectors. For example, the multiple rows of detectors can be arranged partially closely and partially sparsely. In the multiple rows of detectors, detectors corresponding to key detection areas can be arranged closely, while detectors corresponding to non-key areas can be arranged sparsely.

[0098] In embodiments of this disclosure, the detector assembly 20 is configured to receive at least a portion of the X-rays attenuated by the object under test (OB), and acquire an energy integration signal and a photon counting signal corresponding to at least a portion of the X-rays. In other words, by receiving the X-rays attenuated by the object under test (OB) and simultaneously or on-demand acquiring the energy integration signal and photon counting signal, the detector assembly 20, through the synergistic complementarity of the two signals, can integrate the performance advantages of EID, PCD, and SCID, while avoiding the inherent defects of a single signal. This results in performance improvements in material resolution accuracy, scene adaptability, and detection reliability.

[0099] In the detector assembly 20 of the radiation imaging system 100 provided in the embodiments of this disclosure, the crystal layer of at least one row of detectors can be designed as two layers of crystals, with the upper layer being a low-energy crystal to obtain low-energy absorption spectrum data and the lower layer being a high-energy crystal to obtain high-energy absorption spectrum data after absorption by the low-energy crystal. The equivalent atomic number of the object is obtained by fusing grayscale with high and low energy data and dual-energy calibration, thereby generating a pseudo dual-energy image.

[0100] In the radiation imaging system 100 provided in the embodiments of this disclosure, at least one row of detectors may include a single-layer scintillator crystal, and true dual-energy data can be obtained by adjusting the energy of the X-ray source 10 or by superimposing a filter in front of the X-ray source 10, and a true dual-energy image can be generated in one step.

[0101] Return to reference Figure 1 The radiation imaging system 100 may further include a signal processor 70, which may be electrically connected to the detector assembly 20. The signal processor 70 may be configured to receive an energy integration signal and a photon counting signal, and generate a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal. That is, the signal processor 70 may receive the energy integration signal and the photon counting signal output by the detector assembly 20 in any of the above configurations. The signal processor 70 may determine, based on the specific characteristics of the received energy integration signal and photon counting signal, to generate a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal. For example, in some cases, the signal processor 70 may generate a signal processing result for radiation imaging based on both the energy integration signal and the photon counting signal; in other cases, the signal processor 70 may generate a signal processing result for radiation imaging based on either the energy integration signal or the photon counting signal.

[0102] As mentioned above, the inventors discovered through research that, for PCD, the counting period cannot be infinitely short. When two or more photons enter the detector within the same counting period, it will cause electrical pulse overlap and pulse accumulation. This accumulation effect will further lead to a decrease in low-energy counts and an increase in high-energy counts, resulting in distortion of the X-ray energy spectrum and affecting the true result of the image output. Figures 8A to 8B The diagram illustrates the pulse stacking pattern in a photon-counting detector. For a PCD, within one counting cycle, one, two, or even more incident photons may be incident simultaneously, such as... Figure 8A and Figure 8B As shown, four counting cycles are schematically illustrated. For ease of description, they are referred to from left to right as the first counting cycle, the second counting cycle, the third counting cycle, and the fourth counting cycle. The line segments with arrows schematically represent incident photons, and the length of the line segments with arrows schematically represents the energy of the incident photons. Figure 8A The diagram schematically illustrates the input signal incident on the PCD. In the first counting period, one incident photon is incident; in the second counting period, two incident photons are incident; in the third counting period, two incident photons are incident; and in the fourth counting period, three incident photons are incident. That is, two-photon stacking occurs in the second and third counting periods, and three-photon stacking occurs in the fourth counting period. Figure 8B As shown, the equivalent output signal of the PCD, i.e., the measurement signal or measurement energy spectrum of the PCD, is schematically illustrated. In the first counting period, no photon accumulation occurs, and the equivalent output signal of the PCD is consistent with the input signal. In the second and third counting periods, two-photon accumulation occurs, and the equivalent output signal of the PCD is the superposition of the input signals of the two incident photons. In the fourth counting period, three-photon accumulation occurs, and the equivalent output signal of the PCD is the superposition of the input signals of the three incident photons. Therefore, it can be seen that when photon accumulation occurs within one counting period, the measurement signal or measurement energy spectrum of the PCD is inconsistent with the input signal incident on the PCD; that is, the measurement signal or measurement energy spectrum of the PCD does not accurately represent the incident energy spectrum incident on the PCD.

[0103] Further research by the inventors revealed that EID has a linear relationship with the radiation flux, is not affected by the magnitude of the current intensity, and is not affected by the electric field of accumulated space charge. This linear characteristic of EID can be used to perform signal accumulation correction on PCD.

[0104] The following description, using the case of two-photon stacking within one counting cycle, exemplifies the method for signal stacking correction of a PCD using EID. It should be understood that the method for signal stacking correction of a PCD using EID provided in this disclosure is not limited to the case of two-photon stacking, but can also be applied to cases of three-photon stacking or more photon stacking.

[0105] It should be noted that, when the detector assembly includes SCID, the statement "using EID to correct signal accumulation in PCD" can include correcting the photon counting signal of SCID using the energy integration signal of SCID; when the detector assembly includes both EID and SCID, the statement "using EID to correct signal accumulation in PCD" can include correcting the photon counting signal of SCID using the energy integration signal of SCID or EID; when the detector assembly includes both PCD and SCID, the statement "using EID to correct signal accumulation in PCD" can include correcting the photon counting signal of SCID or PCD using the energy integration signal of SCID; and when the detector assembly includes both EID and PCD, the statement "using EID to correct signal accumulation in PCD" can include correcting the photon counting signal of PCD using the energy integration signal of EID.

[0106] For example, the probability p of two photons accumulating is related to the luminous flux N of the incident photons. in The relationship between the time of death τ and the time of death can be expressed by the following formula:

[0107]

[0108] Where τ is the dead time of the PCD or SCID, the dead time of the PCD or SCID refers to the period during which the PCD or SCID cannot respond to newly incident photons while processing a photon signal because its internal circuitry is still in signal processing or reset state. This is the signal reception blind zone that exists in the PCD or SCID during actual operation. The luminous flux N of the incident photon... in This can refer to the average number of incident photons per unit time. For example, the luminous flux N of incident photons can be obtained based on the energy integral signal of EID or SCID. in .

[0109] In the case of two-photon stacking, it can be assumed that the signal output by the detector is the total energy of the two stacked photons, that is, the stacked energy spectrum s of the two photons. pileup (E) and the normalized incident energy spectrum of a single photon in The relationship (E) can be expressed by the following formula:

[0110]

[0111] The operator "*" represents the convolution operation, that is, the stacked energy spectrum s of two photons. pileup (E) equals the normalized incident energy spectrum of a single photon. in The result of the convolution operation of (E).

[0112] Accumulated luminous flux N pileup With incident luminous flux N in The relationship can be expressed by the following formula:

[0113]

[0114] Since two incident photons generate a stacked photon with a probability of p, the probability of losing the original incident signal is 2p. The measured energy spectrum S of the PCD... test (E) can be expressed as follows:

[0115]

[0116] In equations (1)-(4) above, the lowercase symbol s represents the parameter for a single photon, and the uppercase symbol S represents the parameter for photons within a counting period. In equation (4), S in (E) can be understood as the true incident energy spectrum, i.e., the photon energy spectrum without accumulation; the coefficient (1-2p) can be understood as: each time accumulation occurs, 2 photons only give 1 pulse, i.e., for "single photon counting", 1 less event; the accumulation probability p refers to the "event", and each event involves 2 photons, so the proportion of the total number of photons that are discarded is 2p, and therefore the share of single photons that can survive and still be recorded individually is (1-2p). In equation (4), S pileup (E) can be understood as the energy spectrum contributed by the new pulse after stacking and merging. That is, in equation (4), the energy distribution of the first term remains the same, but the total intensity is reduced by 2p; the second term is the additional intensity that is transferred over, which is s in (E) self-convolution.

[0117] Based on the above equation (4), the energy spectrum S measured by PCD can be derived. test (E) Calculate the true incident energy spectrum S in The formula for calculating (E) is shown below:

[0118]

[0119] Since the output of EID (i.e., the measured energy spectrum) is linearly related to the current, it can be used to estimate the luminous flux N of the incident photons. inFurthermore, the measured energy spectrum of EID can be used instead of the incident energy spectrum to estimate the stacking effect. The corrected incident energy spectrum of PCD can be expressed by the following formula:

[0120]

[0121] According to equation (6), in the case of photon accumulation, the output of the PCD (i.e., the measured energy spectrum S) is no longer used directly. test (E) to estimate the incident energy spectrum S of the PCD in (E), but instead uses the EID signal to correct the effects of photon stacking, i.e., the “E” in equation (6) The term is used to obtain the corrected incident energy spectrum of the PCD. It should be understood that the corrected incident energy spectrum of the PCD removes the influence of photon stacking, thus being closer to the true incident energy spectrum of the PCD.

[0122] After obtaining the corrected incident energy spectrum of the PCD, the following equation can be established:

[0123]

[0124] In equation (7), S in_i S represents the incident energy spectrum of the i-th energy window, i.e., the energy spectrum distribution of the i-th energy window incident on the detector. It can be obtained as follows: after dividing the incident energy spectrum of a photon counting detector (PCD) into energy windows (that is, dividing the continuous energy spectrum into several energy windows according to energy ranges), the actual measured energy spectrum data in each energy window reflects information such as the number of photons received by the detector in that energy range. i The equivalent energy spectrum represents the i-th energy window, which is the equivalent energy spectrum emitted by the X-ray source within the i-th energy window. It describes the inherent energy spectrum characteristics of the X-ray source emitting photons in this energy range. It is a decay ratio function at different energies, where The coefficients of the basis functions are related to material properties (e.g., equivalent atomic number, density, etc.). The above equation reflects the attenuation of photons of different energies within various energy windows as rays pass through the material characterized by these coefficients, expressed in exponential form (e.g., ...). This describes the variation of attenuation with energy and material coefficients. Equation is a function related to energy. The attenuation coefficients of different material compositions at different energies are M. kThis refers to the quantity of material components. 'n' represents the total number of equivalent energy spectra (i.e., the energy spectrum emitted by the X-ray source), which is the total number of energy windows obtained after dividing the X-ray source's energy spectrum according to energy windows, corresponding to the range of values ​​i=1,2,…,n. 'N' represents the number of discrete energies in the equivalent energy spectrum, that is, the number of discrete energy points selected after discretizing continuous energy in each equivalent energy spectrum (energy spectrum within an energy window), used to calculate attenuation and other processes in discrete form.

[0125] It should be noted that, unless otherwise specified, in this article, the term "incident energy spectrum" refers to the energy spectrum incident on the detector or detector assembly, the term "measured energy spectrum" refers to the energy spectrum measured by the detector or detector assembly, and the term "equivalent energy spectrum" refers to the energy spectrum emitted from the X-ray source within a certain energy range.

[0126] Figure 9A and Figure 9B These are schematic diagrams of the equivalent energy spectra corresponding to photon counting detectors and energy integrating detectors, respectively. Figure 9A The image shows the equivalent energy spectrum of a photon counting detector (PCD). Figure 9A In the graph, the horizontal axis represents energy (unit: keV), ranging from approximately 20 to 100 keV; the vertical axis represents the photon count, reflecting the number of photons received by the PCD at different energies. Figure 9A The diagram shows multiple curves with different patterns (blue circles, red crosses, green crosses, etc.), representing the energy spectrum distribution detected by PCD under different energy windows. For example... Figure 9B The image shows the equivalent energy spectrum of an energy integrating detector (EID). Figure 9B In the graph, the horizontal axis represents energy (unit: keV), ranging from approximately 20 to 160 keV; the vertical axis represents probability, indicating the probability distribution of photons with different energies. Figure 9B It contains two curves: low energy (blue curve) and high energy (orange curve). The low energy curve has a significant peak at a specific energy (such as about 50 keV), while the high energy curve is relatively flat, with an indistinct peak and an overall probability level lower than that of the low energy curve at its peak.

[0127] Combination Figure 9A and Figure 9B The equivalent energy spectrum shown further illustrates the parameters n and N in equation (7). n represents the total number of equivalent energy spectra, corresponding to the total number of energy ranges. For example, from Figure 9ALooking at the equivalent energy spectrum (corresponding to PCD), the figure shows multiple curves of different patterns. This can be understood as dividing the continuous energy spectrum detected by PCD into multiple energy windows according to certain rules (such as energy range division). Each curve represents the equivalent energy spectrum within one energy window. These energy windows collectively cover the entire energy range detectable by PCD. By analyzing the equivalent energy spectrum within each energy window, the distribution and characteristics of photons in different energy ranges can be studied in more detail. Figure 9B Looking at the equivalent energy spectrum corresponding to EID, there are two curves with different patterns in the figure. This can be understood as dividing the continuous energy spectrum detected by EID into two energy intervals according to certain rules (e.g., low energy and high energy division). In the embodiments of this disclosure, the measured energy spectrum under n energy intervals can be obtained based on the signal processing results of the photon counting signal and the energy integration signal, where n is the sum of the number of energy windows corresponding to the photon counting signal and the number of crystal layers corresponding to the energy integration signal.

[0128] N is the number of discrete energies in the equivalent energy spectrum, that is, the number of discrete energy points selected after discretizing continuous energy in each equivalent energy spectrum (the energy spectrum within each energy range). Figure 9A For example, the energy on the horizontal axis changes continuously, but in actual calculations, it is necessary to discretize the continuous energy range into individual energy points, for example... Figure 9A The blue circles, red crosses, and green crosses in the diagram represent discrete energy points. By selecting a sufficient number of discrete energy points, attenuation processes can be calculated relatively accurately in discrete form, thus approximately simulating the energy spectrum distribution and attenuation law under continuous energy, providing a foundation for subsequent solutions based on discrete energy material information. It should be noted that although... Figure 9B Discrete energy points are not schematically shown, however, in Figure 9B For example, the energy on the horizontal axis changes continuously. In actual calculations (such as the calculation of the attenuation ratio function), it is necessary to discretize the continuous energy range into individual energy points. In the embodiments of this disclosure, N is the sum of the number of these discrete energy points.

[0129] Referring back to equation (7) above, the left-hand side of the equation includes the incident energy spectrum incident on each detector of the detector assembly, and the right-hand side includes the equivalent energy spectrum emitted by the X-ray source and the attenuation ratio function. Optionally, the terms on the left-hand side of the equation (i.e., the left-hand term of the equation) S in_i It is an n-dimensional column vector, and the term S on the right-hand side of the equation i It is an n×N matrix with items It is an N-dimensional column vector. In solving equation (7), the maximum likelihood method can be used for iterative solution, thereby decomposing and obtaining the coefficients of each basis function. And so on, thereby obtaining material information.

[0130] In other words, in the signal processor 70 provided in this embodiment, an equation can be jointly established based on both the energy integration signal and the photon counting signal; and the equation can be solved to obtain a signal processing result for radiation imaging. For example, establishing the equation jointly based on both the energy integration signal and the photon counting signal may include: performing stacking correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal. For example, performing stacking correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal may include: obtaining the luminous flux of the incident photon based on the energy integration signal; obtaining the probability of photon stacking based on the luminous flux of the incident photon and the dead time of the first detector or the third detector; obtaining a first measured energy spectrum corresponding to the photon counting signal based on the photon counting signal; and correcting the first measured energy spectrum based on the energy integration signal, the luminous flux of the incident photon, and the probability to obtain a first incident energy spectrum. For example, as represented by equation (1) above, the luminous flux N of the incident photon can be obtained based on the energy integration signal of SCID or EID. in ;Based on the luminous flux N of the incident photon in The probability p of photon accumulation is obtained from the dead time τ of SCID or PCD. For example, as expressed in equations (2)-(6) above, the probability p of photon accumulation can be obtained from the energy integral signal N. test The luminous flux N of the incident photon in And probability p, for the first measured energy spectrum S corresponding to the photon counting signal test (E) Correction is performed to obtain the first incident energy spectrum S in (E).

[0131] For example, the step of jointly establishing the equation based on the energy integration signal and the photon counting signal further includes: obtaining a second incident energy spectrum corresponding to the energy integration signal based on the energy integration signal; generating an incident energy spectrum based on the first incident energy spectrum and the second incident energy spectrum, wherein the incident energy spectrum is an energy spectrum under n energy intervals, where n is the sum of the number of energy windows corresponding to the photon counting signal and the number of crystal layers corresponding to the energy integration signal; and constructing the left-hand side of the equation using the generated incident energy spectrum. For example, the second incident energy spectrum corresponding to the energy integration signal can be obtained based on the energy integration signal of SCID or EID. For the energy integration signal of SCID or EID, there is no need to consider the stacking effect, and the second incident energy spectrum corresponding to the energy integration signal can be obtained directly. For example, the second incident energy spectrum can be the energy spectrum directly corresponding to the energy integration signal of SCID or EID, that is, the integration branch of SCID or the measurement energy spectrum of EID. Then, the first incident energy spectrum S generated according to equation (6) can be obtained. in(E) (i.e., the corrected PCD measurement energy spectrum) and the directly acquired second incident energy spectrum corresponding to the energy integration signal (i.e., the integral branch of SCID or the measurement energy spectrum of EID) generate the incident energy spectrum. That is, the incident energy spectrum S in equation (7) i This includes the first incident energy spectrum and the second incident energy spectrum. As indicated by the above equation (7), the left-hand side of equation (7) can be constructed using this incident energy spectrum.

[0132] For example, solving the equations to obtain signal processing results for radiation imaging may include: iteratively solving the equations to decompose them into coefficients of multiple basis functions; and obtaining material information based on the coefficients of the multiple basis functions. For instance, during the solution process, a maximum likelihood approach can be used for iterative solving to decompose the equations into coefficients of multiple basis functions.

[0133] In some embodiments of this disclosure, generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal may include: establishing an equation based solely on the photon counting signal in response to the energy integration signal being less than a first preset value; and solving the equation to obtain the signal processing result for radiation imaging. For example, the first preset value may be 1% of the air value. When the energy integration signal output from the integration branch of the EID or SCID is too weak, for example, less than 1% of the air value, it indicates a low flux after radiation transmission. In this case, the energy integration signal output from the integration branch of the EID or SCID is significantly affected by noise interference, and its reliability will decrease significantly; while the photon counting signal output from the counting branch of the PCD or SCID is closer to the original characteristics of the incident energy spectrum and does not require correction from the energy integration signal output from the integration branch of the EID or SCID. When establishing the equation, only the photon counting signal output from the counting branch of the PCD or SCID can be used. In this case, when establishing equation (7), only the photon counting signal output by the counting branch of PCD or SCID can be used, and the equation is still constructed according to equation (7). In equation (7), n is equal to the number of energy windows corresponding to the photon counting signal output by the counting branch of PCD or SCID.

[0134] It should be noted that the "air value" mentioned in this article refers to the reference value of the signal received by the detector when the ray passes through only air (without other objects to be measured). This air value can be used as a reference benchmark for measuring the actual detection signal strength.

[0135] In some embodiments of this disclosure, generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal may include: establishing an equation based solely on the energy integration signal in response to the energy integration signal being greater than a second preset value; and solving the equation to obtain the signal processing result for radiation imaging. For example, the second preset value may be 50% of the air value. When the energy integration signal output from the integration branch of EID or SCID is very strong, for example, higher than 50% of the air value, it indicates a high flux after X-ray transmission. In this case, the energy integration signal output from the integration branch of EID or SCID is less affected by noise interference and has higher reliability; however, the photon counting signal output from the counting branch of PCD or SCID suffers from severe photon accumulation, with not only two-photon accumulation but also a high proportion of three-photon and multi-photon accumulation signals, making accumulation correction difficult. In this case, the equation can be established using only the energy integration signal output from the integration branch of EID or SCID. In this case, when establishing equation (7), only the energy integral signal output by the integral branch of EID or SCID can be used, and the equation is still constructed according to equation (7). In equation (7), n is equal to the number of crystal layers corresponding to the energy integral signal.

[0136] In some embodiments of this disclosure, generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal may include: establishing an equation jointly based on the energy integration signal and the photon counting signal in response to the energy integration signal being between a first preset value and a second preset value; and solving the equation to obtain the signal processing result for radiation imaging. In this case, the energy integration signal output from the integration branch of EID or SCID can be used to correct the photon counting signal output from the counting branch of PCD or SCID, and the equation can be established using the corrected first incident energy spectrum corresponding to the photon counting signal and the second incident energy spectrum corresponding to the energy integration signal. As described above, in this case, when establishing equation (7), the energy integration signal output from the integration branch of EID or SCID and the photon counting signal output from the counting branch of PCD or SCID can be used, and the equation is still constructed based on equation (7), where n in equation (7) is equal to the sum of the number of energy windows corresponding to the photon counting signal and the number of crystal layers corresponding to the energy integration signal.

[0137] Optionally, refer to Figure 1The radiation imaging system 100 may further include a collimator 50, which may be disposed at the emission end of the radiation source 10 (e.g., the end of the radiation source 10 facing the detector assembly 20) to collimate the radiation emitted by the radiation source 10, so that the collimated radiation covers the detector assembly 20 with a preset radiation field. For example, the collimated radiation may be formed into a fan-shaped beam with a relatively wide angle in the row direction, covering each row of detectors in the detector assembly 20.

[0138] Optionally, the radiation imaging system 100 can be a digital X-ray imaging system (i.e., a DR system), and the signal processing results include at least one of transmission grayscale information and material information. For example, the detector component of the radiation imaging system 100 can adopt a combination structure of SCID+EID, wherein EID can include a double-layer scintillator crystal layer, and SCID can output an energy integration signal and a photon counting signal. When the system is working, the X-rays emitted by the X-ray source penetrate the object under test, and the detector component receives the X-rays after attenuation by the object under test. If the energy integration signal output by EID is greater than a second preset value, it is determined that the transmission flux is high and the EID noise is low. Based on the double-layer integration signal of EID, transmission grayscale information is generated. By fusing the low-energy integration signal and the high-energy integration signal according to a preset weight, they are converted into grayscale values ​​to form a grayscale image reflecting the density difference of the object under test. If the energy integration signal output by EID is less than a first preset value, the photon counting signal of SCID is activated, an equation is established according to equation (7), and the basis function coefficients are solved by maximum likelihood iteration to generate material information.

[0139] Optionally, the radiation imaging system 100 can be a computed tomography (CT) system, and the signal processing results include at least one of transmission grayscale information, density information, material information, and basis function coefficient information. For example, the detector assembly of the radiation imaging system 100 can adopt a combination structure of EID+SCID+PCD, and the X-ray source and the detector assembly can synchronously rotate to scan the object under test; for transmission grayscale information, the tomographic grayscale image can be reconstructed based on the energy integration signal of EID through a filtering back projection algorithm, and the grayscale value is positively correlated with the degree of X-ray attenuation; for density information, the fusion data of the energy integration signal and the photon counting signal of SCID can be used, combined with the attenuation database of known standard materials, to establish a mapping model and back-calculate the density value of each voxel of the object under test; for material information and basis function coefficient information, the energy integration signal and the photon counting signal can be used to establish an equation according to equation (7), and the basis function coefficient information can be obtained by iterative solution, and then the material information can be generated through the preset correspondence between the coefficient and the material composition.

[0140] In the radiation imaging system provided in this disclosure, considering the photon accumulation problem caused by the limited counting period of the PCD (Polymer Cancellation Detector), the energy integration signal can be used to correct the photon counting signal, avoiding image artifacts caused by pulse accumulation in a single PCD. This is beneficial for improving the accuracy of material analysis and the quality of the imaging image. In this radiation imaging system, both the energy integration signal and the photon counting signal can be obtained simultaneously. The energy integration signal can be used to correct the photon counting signal for accumulation as needed, or the energy integration signal and the photon counting signal can be used independently as needed. By rationally using both signals under different conditions to provide material analysis results, a synergistic effect can be achieved, thereby improving the recognition accuracy and imaging quality of radiation imaging systems such as DR and CT systems.

[0141] It should be understood that the radiation imaging system provided in this disclosure can be applied to various scenarios such as security inspection, ore sorting, and industrial and agricultural inspection. In at least some scenarios, in order to improve detection speed or obtain image quality with a higher signal-to-noise ratio, the output current of the X-ray source can be set higher, resulting in higher luminous flux per unit area and per unit time of the detector. Although a single EID can adapt to high-flux conditions, it has poor energy spectral resolution and large material reconstruction deviations. While a single PCD can improve energy spectral resolution in these application scenarios, it faces the influence of the accumulation effect, resulting in inaccurate photon counts measured in each energy window, with low values ​​in the low-energy region and high values ​​in the high-energy region, leading to poor reconstruction accuracy and restricting or affecting the application of PCD. In the embodiments of this disclosure, the signals of the two detectors are combined to highlight the advantages of a single detector and compensate for its disadvantages, thereby achieving more accurate material resolution. For example, it can improve the accuracy of ore sorting, the recognition rate of security inspections, and reduce the false alarm rate of security inspections.

[0142] Figure 10 This is a flowchart of a radiation imaging method according to an embodiment of the present disclosure. Figure 10 As shown, the radiation imaging method may include steps S1010 to S1040.

[0143] In step S1010, the radiation source is controlled to emit radiation for radiation scanning of the object under test.

[0144] In step S1020, at least a portion of the attenuated rays from the object under test is received by the detector assembly, and an energy integration signal and a photon counting signal corresponding to at least a portion of the rays are acquired.

[0145] In step S1030, a signal processing result for radiation imaging is generated based on at least one of the energy integration signal and the photon counting signal.

[0146] In step S1040, a radiation image of the object under test is generated based on the signal processing results.

[0147] It is understood that the radiation imaging method can be executed by the signal processor 70, and the relevant functions and steps executed by the signal processor 70 can be incorporated into the radiation imaging method. For the sake of brevity, these details will not be elaborated upon here.

[0148] Figure 11 A block diagram schematically illustrates an electronic device suitable for implementing a radiation imaging method according to an embodiment of the present disclosure. For example, the signal processor 70 described above may include this electronic device.

[0149] like Figure 11 As shown, an electronic device 1100 according to an embodiment of the present disclosure includes a processor 1101, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1102 or a program loaded from a storage portion 1108 into a random access memory (RAM) 1103. The processor 1101 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 1101 may also include onboard memory for caching purposes. The processor 1101 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure. Various programs and data required for the operation of the electronic device 1100 are stored in the RAM 1103. The processor 1101, ROM 1102, and RAM 1103 are interconnected via a bus 1104. The processor 1101 performs various operations of the method flow according to an embodiment of the present disclosure by executing programs in the ROM 1102 and / or RAM 1103. According to embodiments of this disclosure, the electronic device 1100 may further include an input / output (I / O) interface 1105, which is also connected to the bus 1104. The electronic device 1100 may also include one or more of the following components connected to the input / output (I / O) interface 1105: an input section 1106 including a keyboard, mouse, etc.; an output section 1107 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 1108 including a hard disk, etc.; and a communication section 1109 including a network interface card such as a LAN card, modem, etc., a driver 1110, a removable medium 1111, etc.

[0150] Embodiments of this disclosure also provide a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs that, when executed, implement the method according to the embodiments of this disclosure. According to embodiments of this disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium, such as including but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this disclosure, the computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of this disclosure, the computer-readable storage medium may include ROM 1102 and / or RAM 1103 and / or one or more memories other than ROM 1102 and RAM 1103 described above.

[0151] Embodiments of this disclosure also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowchart. When the computer program product is run on a computer system, the program code is used to enable the computer system to implement the radiation imaging method provided in the embodiments of this disclosure.

[0152] Those skilled in the art will understand that the features described in the various embodiments of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

Claims

1. A detector, characterized in that, The detector includes: A semiconductor layer used to receive incident photons and generate electron-hole pairs; Electrode assemblies, disposed on both sides of the semiconductor layer, are used to apply a bias voltage to form an electric field within the semiconductor layer, thereby collecting the electrical signal generated by the electron-hole pairs; and The back-end signal processing circuit includes a signal splitting module, a counting branch, and an integrating branch. The signal splitting module is used to split the electrical signal into two paths. The counting branch includes a threshold comparator and a counter. The threshold comparator compares the amplitude of the input electrical signal with a preset energy threshold, and the counter statistically counts electrical signals exceeding the preset energy threshold. The integrator branch includes an integrator used to accumulate the input electrical signal.

2. A detector assembly, characterized in that, The detector assembly includes at least one row of first detectors, wherein the first detectors are the detectors as described in claim 1.

3. The detector assembly as claimed in claim 2, wherein, The detector assembly also includes at least one row of second detectors, which are energy integration type detectors.

4. The detector assembly as claimed in claim 2 or 3, wherein, The detector assembly also includes at least one row of third detectors, which are photon counting detectors.

5. The detector assembly as claimed in claim 3 or 4, wherein, The energy integration detector includes: A scintillator crystal layer for receiving incident photons and converting the energy of the incident photons into an optical signal; and The sensor layer, which is attached to the scintillator crystal layer, is used to receive the optical signal output by the scintillator crystal layer, convert the optical signal into an electrical signal, and perform integration processing on the electrical signal to obtain the total energy correlation signal of the incident photon.

6. The detector assembly of claim 5, wherein, The scintillator crystal layer has a single-layer structure, and this single-layer scintillator crystal layer is located on the light-receiving surface of the sensor layer, used to uniformly convert the energy of the incident photons into an optical signal; or... The scintillator crystal layer has a double-layer structure, comprising a first scintillator sublayer and a second scintillator sublayer disposed along the propagation direction of the incident photons. The first scintillator sublayer is used to absorb incident photons with a first energy and convert them into a first optical signal, and the second scintillator sublayer is used to absorb incident photons with a second energy and convert them into a second optical signal. The first energy is lower than the second energy. Alternatively... The scintillator crystal layer has a multi-layer structure, which includes m scintillator sub-layers arranged along the propagation direction of the incident photons, where m is a positive integer greater than or equal to 3. The material composition and / or thickness of each scintillator sub-layer are arranged in a gradient along the propagation direction of the incident photons. The m gradient-arranged scintillator sub-layers are used to absorb incident photons in different energy ranges and convert them into m optical signals.

7. A detector assembly, characterized in that, The detector assembly includes at least one row of second detectors and at least one row of third detectors, wherein the second detectors are energy integration detectors and the third detectors are photon counting detectors; The energy integration detector includes: a scintillator crystal layer for receiving incident photons and converting the energy of the incident photons into an optical signal; and a sensor layer, attached to the scintillator crystal layer, for receiving the optical signal output by the scintillator crystal layer, converting the optical signal into an electrical signal, and integrating the electrical signal to obtain a total energy correlation signal of the incident photons; and The scintillator crystal layer has a single-layer structure, located on the light-receiving surface of the sensor layer, and is used to uniformly convert the energy of the incident photons into optical signals; or, the scintillator crystal layer has a double-layer structure, comprising a first scintillator sublayer and a second scintillator sublayer arranged along the propagation direction of the incident photons, wherein the first scintillator sublayer is used to absorb incident photons with a first energy and convert them into a first optical signal, and the second scintillator sublayer is used to absorb incident photons with a second energy and convert them into a second optical signal, wherein the first energy is lower than the second energy; or, the scintillator crystal layer has a multi-layer structure, comprising m scintillator sublayers arranged along the propagation direction of the incident photons, wherein m is a positive integer greater than or equal to 3, and the material composition and / or thickness of each scintillator sublayer is gradient-arranged along the propagation direction of the incident photons, wherein the gradient-arranged m scintillator sublayers are respectively used to absorb incident photons of different energy ranges and convert them into m optical signals.

8. A radiation imaging system, characterized in that, The radiation imaging system includes: A radiation source, used to emit rays for radiation scanning of the object under test; and A detector assembly for receiving at least a portion of the radiation after it has been attenuated by the object under test. The detection component is the detector component as described in any one of claims 2-7.

9. The radiation imaging system as claimed in claim 8, wherein, The detector assembly is configured to acquire an energy integral signal and a photon count signal corresponding to at least a portion of the ray; The radiation imaging system further includes a signal processor electrically connected to the detector assembly, the signal processor being configured to: receive the energy integration signal and the photon counting signal, and generate a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal.

10. The radiation imaging system of claim 9, wherein, The step of generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: In response to the energy integral signal being less than a first preset value, an equation is established solely based on the photon counting signal; and Solve the equations to obtain the signal processing results for radiation imaging.

11. The radiation imaging system as claimed in claim 9 or 10, wherein, The step of generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: In response to the energy integral signal being greater than a second preset value, an equation is established solely based on the energy integral signal; and Solve the equations to obtain the signal processing results for radiation imaging.

12. The radiation imaging system according to any one of claims 9-11, wherein, The step of generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: In response to the energy integral signal falling between the first preset value and the second preset value, an equation is jointly established based on both the energy integral signal and the photon counting signal; and Solve the equations to obtain the signal processing results for radiation imaging.

13. The radiation imaging system according to any one of claims 10-12, wherein, The left-hand side of the equation includes the incident energy spectrum incident on each detector of the detector assembly, and the right-hand side of the equation includes the equivalent energy spectrum emitted by the X-ray source and the attenuation ratio function.

14. The radiation imaging system of claim 12, wherein, The step of establishing an equation based on the energy integration signal and the photon counting signal includes: performing stacking correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal.

15. The radiation imaging system of claim 14, wherein, The stacking correction of the incident energy spectrum corresponding to the photon counting signal based on the energy integral signal includes: The luminous flux of the incident photon is obtained based on the energy integral signal; Based on the luminous flux of the incident photons and the dead time of the first detector or the third detector, the probability of photon accumulation is obtained. Based on the photon counting signal, obtain the first measurement energy spectrum corresponding to the photon counting signal; and The first measured energy spectrum is corrected based on the energy integral signal, the luminous flux of the incident photon, and the probability to obtain the first incident energy spectrum.

16. The radiation imaging system of claim 15, wherein, The method of establishing the equation based on the combined energy integration signal and the photon counting signal also includes: Based on the energy integral signal, obtain the second incident energy spectrum corresponding to the energy integral signal; An incident energy spectrum is generated based on the first incident energy spectrum and the second incident energy spectrum, wherein the incident energy spectrum is an energy spectrum across n energy ranges, and n is the sum of the number of energy windows corresponding to the photon counting signal and the number of crystal layers corresponding to the energy integration signal; and The left-hand side of the equation is constructed using the generated incident energy spectrum.

17. The radiation imaging system of claim 13, wherein, Solving the equations to obtain signal processing results for radiation imaging includes: The equation is solved iteratively, and the coefficients of multiple basis functions are obtained by decomposition; and Material information is obtained based on the coefficients of the aforementioned basis functions.

18. The radiation imaging system according to any one of claims 8-17, wherein, The radiation imaging system also includes a collimator, which is disposed at the emission end of the radiation source and is used to collimate the radiation emitted by the radiation source so that the collimated radiation covers the detector assembly with a preset radiation field.

19. The radiation imaging system according to any one of claims 8-18, wherein, The radiation imaging system is a digital X-ray imaging system, and the signal processing result includes at least one of transmission grayscale information and material information; or... The radiation imaging system is a computed tomography system, and the signal processing results include at least one of transmission grayscale information, density information, material information, and basis function coefficient information.

20. A radiation imaging method, characterized in that, The radiation imaging method includes: Control the emission of rays from the radiation source for radiation scanning of the object under test; The detector assembly receives at least a portion of the radiation after it has been attenuated by the object under test, and acquires an energy integration signal and a photon count signal corresponding to at least a portion of the radiation. Generate a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal; and A radiation image of the object under test is generated based on the signal processing results.

21. The radiation imaging method as described in claim 20, wherein, The step of generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: in response to the energy integration signal being less than a first preset value, establishing an equation based solely on the photon counting signal; and Solve the equations to obtain the signal processing results for radiation imaging.

22. The radiation imaging method as described in claim 20 or 21, wherein, The step of generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: In response to the energy integral signal being greater than a second preset value, an equation is established solely based on the energy integral signal; and Solve the equations to obtain the signal processing results for radiation imaging.

23. The radiation imaging method according to any one of claims 20-22, wherein, The step of generating a signal processing result for radiation imaging based on at least one of the energy integration signal and the photon counting signal includes: In response to the energy integral signal falling between the first preset value and the second preset value, an equation is jointly established based on both the energy integral signal and the photon counting signal; and Solve the equations to obtain the signal processing results for radiation imaging.

24. The radiation imaging method according to any one of claims 21-23, wherein, The left-hand side of the equation includes the incident energy spectrum incident on each detector of the detector assembly, and the right-hand side of the equation includes the equivalent energy spectrum emitted by the X-ray source and the attenuation ratio function.

25. The radiation imaging method as described in claim 23, wherein, The step of establishing an equation based on the energy integration signal and the photon counting signal includes: performing stacking correction on the incident energy spectrum corresponding to the photon counting signal based on the energy integration signal.

26. The radiation imaging method as described in claim 25, wherein, The stacking correction of the incident energy spectrum corresponding to the photon counting signal based on the energy integral signal includes: The luminous flux of the incident photon is obtained based on the energy integral signal; Based on the luminous flux of the incident photons and the dead time of the first detector or the third detector, the probability of photon accumulation is obtained. Based on the photon counting signal, obtain the first measurement energy spectrum corresponding to the photon counting signal; and The first measured energy spectrum is corrected based on the energy integral signal, the luminous flux of the incident photon, and the probability to obtain the first incident energy spectrum.

27. The radiation imaging method as described in claim 26, wherein, The method of establishing the equation based on the combined energy integration signal and the photon counting signal also includes: Based on the energy integral signal, obtain the second incident energy spectrum corresponding to the energy integral signal; An incident energy spectrum is generated based on the first incident energy spectrum and the second incident energy spectrum, wherein the incident energy spectrum is an energy spectrum across n energy ranges, and n is the sum of the number of energy windows corresponding to the photon counting signal and the number of crystal layers corresponding to the energy integration signal; and The left-hand side of the equation is constructed using the generated incident energy spectrum.

28. The radiation imaging method as described in claim 24, wherein, Solving the equations to obtain signal processing results for radiation imaging includes: The equation is solved iteratively, and the coefficients of multiple basis functions are obtained by decomposition; and Material information is obtained based on the coefficients of the aforementioned basis functions.

29. An electronic device comprising: One or more processors; Memory, used to store one or more computer programs. The characteristic feature is that the one or more processors execute the one or more computer programs to implement the steps of the method according to any one of claims 20 to 28.

30. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 20 to 28.

31. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 20 to 28.

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